Planetary Radio • Feb 22, 2023

Martian rock collecting: From meteorites to Mars Sample Return

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Meenakshi Wadhwa

Planetary Scientist and Isotope Geochemist, principal scientist for Mars Sample Return at NASA JPL, School Director and Foundation Professor in the School Of Earth and Space Exploration at Arizona State University

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Sarah Al-Ahmed

Planetary Radio Host and Producer for The Planetary Society

Exciting updates to the plans to return samples from Mars to Earth are underway. Meenakshi Wadhwa, principal scientist for Mars Sample Return at NASA JPL, shares what we have learned from our studies of Martian meteorites and fills us in on the upcoming Mars Sample Return missions. Stick around for our review of the night sky and a look back at this week in space history in What’s Up with Bruce Betts.

Mars sample return concept illustration
Mars sample return concept illustration This illustration shows a concept for multiple robots that would team up to ferry to Earth samples collected from the Mars surface by NASA’s Mars Perseverance rover.Image: NASA/ESA/JPL-CalTech
Perseverance's backup sample depot
Perseverance's backup sample depot This photomontage shows 10 sample tubes deposited onto the Martian surface by NASA's Perseverance rover. Shown from left are "Malay," "Mageik," "Crosswind Lake," "Roubion," "Coulettes," "Montdenier," "Bearwallow," "Skyland," "Atsah," and "Amalik." Deposited from Dec. 21, 2022, to Jan. 28, 2023, these tubes represent a backup collection of rock cores and regolith that could one day be returned to Earth. Perseverance will be collecting more samples on its journey that will be considered the primary samples for return, but these backups are available in case anything happens to the rover. NASA released this photomontage on Feb. 14, 2023.Image: NASA/JPL-Caltech/MSSS

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How many failed missions were attempted to Mars before Mariner 4 succeeded?

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Of the people on board the International Space Station (as of Feb 15, 2023), who has had the most spaceflights?


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Question from the February 8, 2023 space trivia contest:

What astronaut included his two rescue dogs in his official NASA photo?


Leland Melvin was the astronaut that included his two rescue dogs in his official NASA photo.

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Leland Melvin with his dogs NASA astronaut portrait of Leland D. Melvin with his two rescue dogs, Jake and Scout.


Sarah Al-Ahmed: Looking forward to Mars Sample Return this week on Planetary Radio. I'm Sarah Al-Ahmed of The Planetary Society with more of the human adventure across our solar system and beyond. The international effort to collect and return material from the Red Planet is ramping up. This week, Meenakshi Wadhwa, principal scientist for Mars Sample Return at NASA's Jet Propulsion Laboratory joins us to share the exciting updates to the plan. You may have also noticed the dazzling light in Venus and Jupiter in the recent night Sky. Bruce Betts the chief scientist of The Planetary Society will pop in for What's Up to tell us more. This week, members of The Planetary Society's communications and space policy and advocacy teams gathered for retreat at our headquarters in Pasadena, California. We have a lot of exciting upcoming projects to share with you all in the future. But the additional work in bonding this week meant that our team didn't have time to prepare our usual space mission briefings. I promise that we'll be back to our regularly scheduled updates from the World of Space News in next week's show. As always, you can learn more about what's going on in space in The Planetary Society's weekly newsletter, The Downlink. Read it or subscribe to have it sent to your inbox for free every Friday at Humans have been exploring Mars with robotic spacecraft since the 1960s. In that time, we've learned a lot about the red planet and its history. We've discovered that liquid water existed on the surface in the past. The planet once had a warm, wet environment that could have supported life as we know it. But there are so many mysteries that we've yet to solve. How did the planet change over time? What was the atmosphere like? How long did its oceans last, and did life once exist on Mars? The answers to these questions are captured in the Martian rocks, the soil, the terrain. Each grain of dust carries a thousand untold stories as they blow across the desolation of what was once a world so much like our own. Humans have done an amazing job of piecing together the mysteries of Mars from afar. But despite our advances in space technology, there are some questions we just can't answer without bringing bits of the red planet home to our pale blue dot. Just one rock from Mars and an earth-based laboratory could revolutionize our understanding of that world and our place in space. Mars Sample Return is the next step in that journey. It's a series of missions by NASA and the European Space Agency to return samples from the Martian surface to earth. If everything goes according to plan, we'll have the first samples from another planet by the early 2030s. The Perseverance Rover, which is already on Mars, has been gathering precious samples in preparation. Our guest this week is Dr. Meenakshi Wadhwa called Mini by those who know her. She's a planetary scientist and isotope geochemist who's now the principal scientist for Mars Sample Return at NASA's Jet Propulsion Laboratory. She's also the school director and foundation professor in the School of Earth and Space Exploration at Arizona State University. During her time at ASU, she served as the director of the Center for Meteorites Studies for over a decade. She studies Martian meteorites to learn more about what bits of Mars can tell us about its history and about our solar system's formation. She's here to give us an update on the Mars Sample Return mission, what I consider to be one of the most exciting upcoming missions of our lifetimes. Hi Mini. Thanks so much for joining me on Planetary Radio.

Meenakshi Wadhwa: Great to be here. Thanks a lot, Sarah.

Sarah Al-Ahmed: Humans have been studying Mars from afar for generations. But we are so close to finally actually having samples of Mars here on Earth. As a geologist and someone that's working on this Mars Sample Return mission, that's got to be so exciting for you.

Meenakshi Wadhwa: It is just incredibly exciting. I mean, I started my graduate career studying Mars meteorites. When I first actually found out that there were meteorites from Mars that there were actual samples that we thought might be from Mars, I mean, that just blew my mind. I mean, I just thought, "Oh, my God. Here I am. I'm a geologist. I'm vicariously able to be a geologist on Mars." But I soon realized that meteorites, they're useful in terms of understanding some things about Mars, these meteorites from Mars. But there's some things about these rocks that we don't understand the geologic context where they came from on Mars. They're certainly not representative of the planet as a whole. They're a very small subset of the kinds of rocks that are hard enough to be ejected from the surface of the planet. They really don't record the full geologic history of the planet by any means. They've been weathered. Sitting here on earth, they've been weathered and contaminated and altered. I thought at the time, "Hey, wouldn't it be just wonderful to actually be able to go to Mars and collect samples and bring them back?" I won't say how long ago that was, but that was a long, long time ago. I've been dreaming of Mars Sample Return since then. It's always been 10 years in on the horizon. But this is as real as I've ever felt that it was going to be that it's going to happen. We're already collecting samples. Perseverance is already collecting samples on Mars. We've already established a depot, first depot of samples that we have deemed scientifically return worthy. Yeah. It's super exciting.

Sarah Al-Ahmed: Oh, there's so much going on there. I mean, have you ever personally found a Martian meteorite? I know you've spent a huge amount of time studying them.

Meenakshi Wadhwa: I've been to Antarctica for two field seasons. I spent two and a half months there a couple of times hunting for meteorites, and we found a lot of different meteorites. We actually did find, I believe in the field season that I was in at least one Mars meteorite. I found some meteorites of course in the field, but I doubt I found a Mars meteorite myself.

Sarah Al-Ahmed: How do we actually determine the source of these meteorites? What is it about them specifically that tells us that they're from Mars?

Meenakshi Wadhwa: It's a bit of a detective story there. These rocks actually contain little pockets of glass so that the glass is actually melted rock, which basically captured some of the Mars atmosphere. What happened was that at some point in the past, and we think maybe a million years ago, up to maybe 20 million years ago for some of these Mars meteorites, so it was a large impact on the surface of Mars, and it kicked out these crustal rocks from the surface. In the process it actually melted little pockets of the rock, which sucked up some of the Mars atmosphere at the time. Then of course, it solidified almost immediately the glass. That glass actually contains these little bubbles of Mars atmosphere. When you heat up little portions of these rocks that are the glassy material, you release these gases and lo and behold, they have the exact composition of the Mars atmosphere as we know it. We know the Mars atmosphere composition quite well at this point because a number of our rovers have actually measured the compositions. Most recently Mars Science Laboratory did. In fact, we've known the composition. We know it better now. But we knew the composition after Viking measured that composition in the late 1970s there. We were able to make a perfect connection there between these meteorites, which contained basically this Mars atmosphere. Of course, the fact that these likely came from Mars as a result of some kind of impact.

Sarah Al-Ahmed: As you said before, there's a difference between what we can learn from meteorites because we can't really localize them where they came from on Mars. What is it about these new Mars Sample Return samples that will teach us different things about Mars that we couldn't determine from these meteorites?

Meenakshi Wadhwa: For one thing, the Mars meteorites that we have in our collection, they are all what we call igneous rocks. What that means is that they solidified from magma. Those are the kinds of rocks that are hard enough to survive the kind of process that it takes to eject and then transport these rocks from Mars to earth. What we don't have in these Mars meteorites are sedimentary rocks. The sedimentary materials, these are water lane rocks and we find them all over the earth, of course, and they've been deposited by rivers and the ocean. There's a lot to be learned about the past history of Mars, especially the history of water on Mars from studying sedimentary rocks. That's actually really been one of the key types of materials that Perseverance has been after. The whole point of going to Jezero Crater was to be able to look for these kinds of sedimentary materials that were deposited possibly by a lake that might have been present within the crater at some point in the past. There's also a river delta in the area where Perseverance has been collecting samples. Some of the delta-lake sediments would be really interesting. Those are the kinds of materials that Perseverance has been collecting. We've also, of course, collected some igneous rocks from the crater bottom, Jezero Crater bottom. We'd actually expected to find all sedimentary rocks, but it was actually serendipitous that we found that the crater floor is actually made up of igneous rocks. We've got a diversity of rock types in the Perseverance collection, also some minerals that were created in these igneous rocks as a result of interaction with water. We've got some really, really interesting materials that are not represented in Martian meteorites. Of course, I mean the hope is that these rocks that are collected by Perseverance are going to be really clean, pristine in terms of not being contaminated by earth environment. It's going to tell us a lot more about the history of Mars and certainly things that we can't really hope to learn from meteorites.

Sarah Al-Ahmed: Perseverance has been adventuring in Jezero Crater for two years. In fact, this episode will be airing just a few days after the second anniversary of its landing on Mars, which is fantastic.

Meenakshi Wadhwa: Yes.

Sarah Al-Ahmed: The images that we're getting back of these sedimentary layers in that river delta have been frankly mind-blowing. The first time I saw it, "That looks just like the sediments that we see here on earth." I wish that we had the opportunity to bring back every single sample that Perseverance collects. But how are we making the decision between which samples to return and what happens to the ones that we leave back on Mars?

Meenakshi Wadhwa: As you know, we just established a depot on the surface of Mars. That depot has 10 sample tubes. The plan for Perseverance, while it was exploring Jezero Crater and the rocks within Jezero was to actually collect for every rock that was sampled to collect a pair of samples. The goal there was to basically have one sample that we would deposit in the depot and have another one of a pair onboard Perseverance to take beyond the crater. Perseverance in total has 43 sample tubes, 5 of which are witness tubes. That is just basically ... Those tubes are useful for characterizing some of the rover-generated contamination, for example. But there are, in addition to these 5 witness tubes, there are 38 sample tubes. Of those 38 tubes, the goal was to collect a pair of samples from each rock within the crater. Then after we establish the depot at that point, then we would start basically ... The plan is to start collecting single samples. At this point in the depot that we located within Jezero Crater at the Three Forks region, we've got a stash of 10 tubes of which one is a witness, and one of them is actually an atmosphere sample. There are eight rock samples that are in that depot, and all eight of those actually have a pair that's onboard Perseverance already. This little depot that we have, it's an insurance policy. It really is a backup just in case something happens. Because Perseverance is supposed to be the prime delivery pathway for us to deposit the samples that are being carried on it to bring it to the Lander, that's going to then launch these samples into orbit and then eventually to the earth. At the moment, we've got the pairs of those eight samples that are on board and then the rest of the tubes. In total, we're going to have maybe one or two extra tubes, then the slots that are available to carry the samples back. The sample canister that's going to be coming back has 30 slots in it. We're going to have maybe a couple of extra tubes in case something happens or we're not able to collect a sample. Just for a contingency sake, we've got a couple extra. Yeah. I mean, we may have to make a decision about which one or two tubes to not bring back. But that's going to happen probably in a few years time and we'll have some time to think about it We'll have a great beautiful set of samples to bring back that'll represent the diversity of materials from all of the exploration area that Perseverance will have been to.

Sarah Al-Ahmed: This brings up an interesting topic, which is that last year there was announcement that there was some changes to the Mars Sample Return mission. The primary ideas that they want Perseverance to bring the samples back to the Mars Ascent Vehicle, but in the event that doesn't work, there are two helicopters that are coming along for the journey. Can you tell us a little bit about those?

Meenakshi Wadhwa: Yeah. That's been an exciting development. The original architecture when we first started thinking about Mars Sample Return had been to bring along a sample fetch rover that would help to collect the samples that would've been deposited by Perseverance on the ground and then bring them to the Sample Retrieval Lander ... or the Mars Ascent Vehicle on the Sample Retrieval Lander. As a result of refining the architecture, it was actually ... Also because Ingenuity has been performing so well on Mars over 40 flights at this point, and it's really going strong. We realized that we had the option to actually use helicopters as a backup option. The other thing that we found out is that we expect Perseverance to be healthy and be able to do the job when we need to deliver the samples to the Lander. In estimations of Perseverance's lifetime and performance, we were able to refine those as well and basically confirm that Perseverance is likely to be healthy enough to be able to do the job. The architecture has been refined now and Perseverance is the main delivery pathway. The exciting thing of course is that, yeah, we do have these two helicopters that we are going to bring along. They're going to be very similar to Ingenuity. There's going to be a lot of heritage that is associated with this experience that we have, this very successful experience that we have with Ingenuity. The couple of things that'll be different about these helicopters, one is that they're going to need to be able to grapple or grip a sample tube. Then the other is to have a little bit of mobility. Some wheels that are going to allow them to position themselves over a sample tube, for example, to grip it and bring it to the Lander.

Sarah Al-Ahmed: Yeah. How are they actually going to pick up these samples in the event that they need to, are you testing grabbing arms or some kind of chopper thing on the bottom of the helicopter?

Meenakshi Wadhwa: No chopper thing. There's going to be a gripping capability, and that's still something that's being developed at this point. They're going to try to keep it as simple as possible. We don't want to complicate things too much. Basically, it's going to be a small arm that's going to reach out and be able to grip a single tube.

Sarah Al-Ahmed: One of the challenges that Ingenuity faced while it's been on Mars and it's a happy challenge because it only occurred because Ingenuity has lasted way longer than expected. But when the seasons changed on Mars, it necessarily meant a change in the air density, which the team had to account for in order to make Ingenuity continue doing its flight. Is the timing of Mars Sample Return in any way affected by the changing seasons on Mars knowing that we need these helicopters to actually lift off and potentially carry samples?

Meenakshi Wadhwa: We are trying to design these helicopters to be able to accommodate at least some changes in atmospheric density. They're going to be capable, for example. I mean within Jezero Crater, the air density is a little bit different than 500 meters above that beyond the crater. The elevation is a little bit different. The air density is going to be a little bit different there. These helicopters are going to be designed to be able to accommodate that difference as well. Yes, absolutely. I mean, I think the plan is to be able to design them to be able to perform under the set of conditions that we expect at the time that we are going to be seeking to collect these samples. This is a backup plan. Again, hopefully Perseverance is going to be our primary pathway.

Sarah Al-Ahmed: Yeah. Far it's doing well. I mean, I fully believe after seeing all of these other Mars rovers completely outlast what we expected that Perseverance is going to go strong for quite a while and maybe still bring that little rock that it's been hanging out in its wheel carry that along for the ride with it.

Meenakshi Wadhwa: Exactly.

Sarah Al-Ahmed: These changes to the mission have been so exciting that we wrote an article on this subject just a few months ago. I'll link that underneath all the other information on the page for this episode at for anyone who wants to learn more of the details. But getting all of this gear to Mars in order to accomplish the sample return is going to take more than one launch. Can you give us any updates on the latest launch dates for the Earth Return Orbiter and the Sample Return Vehicle?

Meenakshi Wadhwa: Yes. The current plan is for the set of launches to be no sooner than 2027. Basically at the present time, we are expecting that we would launch the Earth Return Orbiter in 2027, and then the Sample Retrieval Lander would depart or be launched in 2028. That's our current plan. We're proceeding with that assumption.

Sarah Al-Ahmed: Does that mean that we're actually going to get the samples back here on Earth?

Meenakshi Wadhwa: Yeah. That means we'll have the samples back 2033.

Sarah Al-Ahmed: That's so exciting. That's less than a decade away.

Meenakshi Wadhwa: I know. I know. Yeah. It's really exciting for me to think about that, because I've been really dreaming about this moment for such a long time, and this actually is starting to really ... It feels real at this point because things are happening, wheels are in motion, and we are collecting rocks on the surface of Mars and we're going to bring them back.

Sarah Al-Ahmed: Yeah. They're going to land here in the United States and Utah, is that right?

Meenakshi Wadhwa: Yeah. The Utah Test and Training Range.

Sarah Al-Ahmed: Why was that the site that was selected for this landing?

Meenakshi Wadhwa: Well, we have had a number of other sample returns, including the Stardust mission from the comet that used the same area, the Genesis mission return there too. I think we have experience with this particular site. It seems like a good place because obviously, there's not a lot of vegetation or human population there, of course, and there's a big area for us to work with. Obviously, we plan to have fairly well constrained landing parameters for when we return the canister samples, the earth entry vehicle, which is going to be bringing back the little sample, the orbiting sample canister. It's mainly that we do have a lot of experience with this particular site.

Sarah Al-Ahmed: We'll be right back with the rest of my interview with Meenakshi Wadhwa after this short message.

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Sarah Al-Ahmed: With previous sample returns from other missions, say the samples that we got back from Asteroid Ryugu, in a lot of cases, they just crash those samples straight into the earth. Is that going to be the situation here?

Meenakshi Wadhwa: For Mars Sample Return, we really wanted to make the planning for the landing of the samples on Earth as robust as possible against any kind of failure. The previous sample returns that we've had in the Utah Test and Training Range, the Stardust sample return for example, that had a parachute that helps to slow down the capsule. The Genesis sample, on the other hand, it was also planned to have a parachute there, but it did not deploy for some reason. Basically it ended up that obviously the capsule crashed. We were able to, of course, get a lot of science still from that, but we don't want that obviously to happen with Mars Sample Return. We wanted to make the capsule really robust against any kind of breakage upon landing. The idea is to actually not use a parachute and make the system strong enough to be able to withstand the impact at the speed that we expected to basically impact the Earth. We've done a number of tests to test that, and we'll be obviously doing many more and making sure that that's a robust system.

Sarah Al-Ahmed: Yeah. Is there any concern that that deceleration will in any way impact the samples? Maybe break them up a little bit?

Meenakshi Wadhwa: No. I mean, I think, again, this is something that we have been testing and will be testing further as well. The capsule is designed and the sample canister is designed to enclose the sample tubes in a way that it kind of protects the samples adequately against any kind of disruption and mechanical breakage and things like that. There's a lot that has to go into the design and implementation of these systems, but they are being designed with that in mind to make sure that the samples are protected against any kind of damage.

Sarah Al-Ahmed: These samples are going to tell us a lot about the history of Mars. But one of the ultimate goals for this project, and one of the primary reasons why we landed Perseverance in Jezero Crater because we want to learn more about the watery history of Mars and potentially its habitability. If we do go through these samples, what are some clues that might actually hint toward the watery history of Mars or specifically life on Mars?

Meenakshi Wadhwa: We already know from previous missions, the rover missions that have been there, Mars Science Laboratory, and even Spirit and Opportunity and all of the missions before that, that there is evidence of liquid water on the surface of Mars. There's obviously a lot that we've learned from these previous missions. But at this point, the goal of bringing the samples back is to really assess in a very thorough manner whether there's evidence of ancient life in these rocks. We know that there was water, but was that environment, the water rich environment that we're looking at, in which some of these sedimentary rocks were deposited, was it capable of actually supporting life in the past? One of the things that I also want to make clear is that the current environment on Mars and the conditions especially near the surface, are such that we don't expect that there will be any extent life. What we're looking for is evidence of ancient life. Basically, I think we'll be able to perform, we'll be able to bring to bear the full arsenal of state-of-the-art technologies and techniques at a present in earth based laboratories to studying these rocks. We'll be able to study these samples in these synchrotrons very, very high resolution and be able to image the samples at very, very high resolution at nanometer scale or less. We'll be able to see if maybe there's things that look like potentially fossilized materials in there. Yeah. The hope is to be able to really study these samples potentially at the atomic scale and be able to learn a lot about past habitability and past conditions on the surface of Mars and how Mars evolved as a planet.

Sarah Al-Ahmed: Yeah. That would be the jackpot right there. If we could find fossilized bacteria or something in these samples, that would be amazing. This is funny because last summer I was on an airplane and as you do when you're just kind of hanging out on an airplane, I was watching a random movie and the movie I watched was called Life with Rebecca Ferguson and Ryan Reynolds. The basic plot of this movie was that Mars Sample Return, return samples to the International Space Station. The scientists there find out that there's actually life in these samples. I'm not saying there's going to be life in these samples, that's highly, highly unlikely. But this movie did bring up an interesting point, which is what kind of quarantine might we be giving these samples? Are we going to be treating them the same way that we did with samples from asteroids and comets or samples from the moon?

Meenakshi Wadhwa: Of course, I mean, movies do like to sensationalize things as I just talked about here. The current evidence and everything that we know about Mars at the present time from having been there with rovers and with orbiting missions and studied Mars for a long time, of course, the NASA specifically, I mean, we've been sending these orbiters and rovers there for a while now. We know that at the present time, the surface environment or Mars is not a very hospitable place. In the past, yes, absolutely. I mean, we do see evidence that there was liquid water on the surface. There might have been standing bodies like lakes within Jezero Crater. We are looking for evidence of ancient life. But at the same time, I think we are still in the interest of being very cautious, just making sure that things are as they should be or as we expect. These samples are going to be treated as if they were hazardous to start with. But I think the plan is to have them be enclosed and quarantined within a BSL level 4 type facility that's a clean facility. They will be assessed. There'll be an initial period when we will verify that these are safe to be distributed. Then they will be distributed ultimately to all the best laboratories in the world to make the analyses. There's also the possibility, of course, that we could sterilize some component of the samples and distribute the samples early to make sure that we get some really, some exciting science results early. The plan is definitely to treat these samples very carefully and to make sure, of course, that there are no untoward impacts as a result of bringing these samples back. Again, the probability of any kind of extended life in these samples is minuscule, extremely, extremely, extremely small. But we are going to treat it with an abundance of caution, and I'm going to basically quarantine them and make sure that these are safe before we release them for analysis.

Sarah Al-Ahmed: Thanks for answering that question. I have to add it in there because our audience on social media asks this all the time. I want to make sure that they feel safe knowing that these samples will be treated carefully.

Meenakshi Wadhwa: Absolutely.

Sarah Al-Ahmed: Will you be personally involved in actually investigating some of these samples when they return to earth?

Meenakshi Wadhwa: I sure hope so. I've really obviously spent much of my career studying Mars from the perspective of these Mars meteorites and to have some actual samples back. I would love to actually be able to analyze some in my laboratory. But yeah, I mean, I'm hoping for that. Absolutely.

Sarah Al-Ahmed: This is an international mission between the European Space Agency and NASA. How can we make sure that everyone in the world benefits from these samples? Are other space agencies going to ask for some of these samples so they can test them as well?

Meenakshi Wadhwa: These samples are absolutely going to be made available to the best laboratories, the best investigations, to the best scientists in the world. It's not going to be just the scientists in the US and just the scientists in Europe. They will be made accessible for the entire science community at large. Yes. I think certainly NASA and ESA are the primary stakeholders in this in terms of the investment being made towards bringing these samples back. But this is going to be humanity's legacy. I mean, this is going to be such an incredible achievement. I mean, it's the most ambitious robotic mission that NASA and EISA have ever done. We'll learn so much from this, but we'll only learn so much only because we plan to include the whole world in this adventure. I think the best scientists and the best laboratories should certainly have access no matter where they are.

Sarah Al-Ahmed: If we did find some evidence of life in these samples, what would that mean to you personally after all these years of just hoping to be a Martian geologist?

Meenakshi Wadhwa: To me, it's a bigger question than just the question about life in these rocks. That's of course a fundamental importance, and I think everybody in the world understands the importance of that. I think it would be a game changer, of course, if there was evidence that showed that there might have been life in the past on Mars. But at the same time, I mean to me personally as a planetary scientist and a geologist, I look at it holistically as understanding the history of this planet and the evolution of life possibly on it is one part of that. From the perspective as a human being, of course, I mean, knowing that life may have originated on another place in the solar system that does change how we think about ourselves and about our place in the solar system and in the universe. I mean, obviously, it's going to have wide-ranging implications, not just in the sciences, but in the humanities and how we think of ourselves as what it means for us as humans on this planet at the current time. But for me as a scientist, I'm interested in understanding the planet as a whole and life, the evolution of life on it is a part of that.

Sarah Al-Ahmed: Yeah. I know that your passion for geology started when you were a small child. I've heard online that a big part of why you got into this field is because you grew up in India looking up at the Himalayas. How did you go from studying earth rocks to falling in love with Mars specifically?

Meenakshi Wadhwa: Yeah. It wasn't a linear path by any means. I mean, I started to study geology when I was living in the northern part of India, again, in the foothills of the Himalayas. I was always just really fascinated by these incredible forces in nature that could produce these tremendous mountain ranges. You'd be able to find fossils in these rocks that were these mountains. Clearly, at some point in the past, these rocks were somewhere in at the bottom of the ocean, and then things ... tectonics brought these to the surface and mountain range. I mean, to me, it was just really incredibly fascinating to imagine what the past of our own planet looked like and how things have changed. It was almost like learning about another planet altogether. If you look into the deep time on the earth, it's not the same planet as it is today. Just as part of that, I mean, I kind of felt like, "Hey, wouldn't it be just super cool if we could understand the geology of other planets in our solar system and the same kind of detail that we understand from our own planet and use the same kind of geological tools to do that?" It was just kind of a dream at that point. When I went, started to go to graduate school, I really didn't know that there was such a thing as Mars meteorites. It just kind of blew my mind that, "Hey, you've got these rocks that formed on another planet next door, on Mars, and these rocks were ejected and we have them as meteorites now." But I can apply the same kinds of tools that apply to earth rocks and learn something about the geology of Mars. I just love doing that. That was really kind of what got me hooked studying rocks from other places in our solar system, which of course, meteorites are representing all kinds of asteroids. We have meteorites we think are from the moon, of course, maybe we have a lot of lunar samples from the Apollo missions, and hopefully we'll have some from the Artemis program too soon. But learning about the record of these rocks tells us something about the planets on which they evolved. I just was fascinated by that. That's what brought me here. But I don't know if that's ever going to be possible in my lifetime, but I hope that there'll be geologists that'll get to explore Mars firsthand. In the meantime, I'm just thrilled that we're going to be able to bring back some rocks from that planet within a decade.

Sarah Al-Ahmed: It is so exciting. I'm sure out there right now is a whole new generation of children that are just now falling in love with space. Maybe someday they'll be the ones walking around on the surface of Mars doing this science. It's really exciting.

Meenakshi Wadhwa: I know. It is super exciting.

Sarah Al-Ahmed: What would you say to those kids about chasing that dream? I know that you've had to overcome so many things in order to achieve this moment for you working on Mars Sample Return, what advice would you give them?

Meenakshi Wadhwa: I would just tell them to follow their dreams. I mean, I think there's so much exciting thing. There's so much that's happening in space, especially right now with our ability to explore places that we never dreamed of before. We're going to go back to the moon very soon, hopefully. Hopefully we'll be able to have humans on Mars not too long into the future as well. I'm hoping that it'll be within my lifetime for sure. There's so much excitement. I mean, I think especially with commercial space and all of the interest in exploring other places. So much happening, even with exoplanets, we're learning so much more about the workings of our universe and how common planets really are and the habitability of these places. This is a super exciting time to be someone just starting out, going to school and learning about these things. The world's going to be a much different place 10, 20 years from now, and so much is going to be happening. I think there'll be so many great opportunities to be part of this exciting space exploration and planetary exploration. I think just follow your dreams.

Sarah Al-Ahmed: These are the moments I dreamed of when I was a child, and I'm so excited for everyone that gets to be a part of this in the future.

Meenakshi Wadhwa: I know.

Sarah Al-Ahmed: Well, thank you so much for talking with me, Mini. I can't tell you how excited I am about this mission and all of us here at The Planetary Society. We really want to wish you and everyone on your team good luck as you undertake this, because this might be one of the coolest missions in the history of space exploration.

Meenakshi Wadhwa: I absolutely believe that. Not that I'm biased or anything. But yes, thank you so much, Sarah. It's been great talking to you.

Sarah Al-Ahmed: To say that I'm looking forward to Mars Sample Return would be an astronomical understatement. I cannot wait to learn more. I'm so excited for people like Mini who've dedicated their lives to helping humanity solve the mysteries of Mars. I imagine that one day I'll see an image come through my social media feed of Mini in a clean room with Mars rocks living out her dreams as a Martian geologist. Now we turn to Dr. Bruce Betts, the chief scientist of The Planetary Society for What's Up and our space trivia contest. Hi Bruce.

Bruce Betts: Hi, Sarah.

Sarah Al-Ahmed: What's up Bruce?

Bruce Betts: All sorts of hunky-dory, swell, keen, peachy stuff.

Sarah Al-Ahmed: That sounds very nice and lovely. I would like to hear about that.

Bruce Betts: Venus now just dominating over in the west after sunset, looking super, super bright. Right when this show comes out on February 22nd, it'll be hanging out next to the crescent moon. But then the moon over the next five or so days will migrate up across the sky and end up next to Mars on February 27th. Jupiter's above Venus, but it's closing in on it. March 1st, Jupiter and Venus, the two brightest planets in the night sky brighter than the brightest star in the night sky will hit each other and explode. No, no. But they will get very close to each other as seen in the sky about the equivalent of one moon diameter apart about half a degree. It will look cool over in the west. That's March 1st. You can watch them grow closer to each other over the next few days and then grow apart after that.

Sarah Al-Ahmed: Yeah. A bunch of our planetary society coworkers were walking to dinner the other night, looked up in the sky and the two shiniest dots in the sky, clearly Venus and Jupiter. But we had to think for a second, which one was, and clearly Venus was the shinier one.

Bruce Betts: Venus, it's so shiny.

Sarah Al-Ahmed: If you catch the two and you're confused about the two shiny dots, go with Venus. That's the shinier one.

Bruce Betts: Shiny. All right. Let us move on to this weekend space history. We'd start with a dark note. But a remembrance, which is 1966, the Gemini 9 prime crew of Elliot See and Charles Bassett crashed in their T-38 and were killed. They switched to a different crew. We remember them. On a much happier note, 2007 New Horizons headed out to Pluto thought, "Hey, I will stop by Jupiter, or at least flyby really, really fast and get some really cool data." This week, 2007 New Horizons flew past Jupiter and a few years later would go past Pluto.

Sarah Al-Ahmed: Those New Horizons images to this day are just absolutely bonkers. I still sometimes look at that picture of Pluto and just think about how much effort it took that we got there, and how beautiful those pictures are. I can't say it enough. If you haven't seen these pictures of Pluto, please look them up. It's worth it.

Bruce Betts: Yeah. The whole Pluto system, quite awesome. Pretty much everywhere we go, more complicated than we ever imagined.

Sarah Al-Ahmed: Vastly more complicated than I thought it would be, for sure.

Bruce Betts: Speaking of complicated, we move on to [inaudible 00:40:56]. All right. That I didn't know where that one was going. It was kind of a surprise for me too. I worked pretty hard trying to not repeat random space facts in over 20 years, and I did it for years before that. It's tricky. I'm cheating a little bit because I'm combining two, but I just think it's so cool. I'm going to give a combined two that in the distant past I've used. We just had the Super Bowl for those paying attention to American Football. At the start of the game, they of course do the coin flip. If our solar system out to Neptune is the size of that coin sitting there on the field, the nearest star system, Alpha Centauri would be about four football fields away. But wait, don't order yet. The Milky Way galaxy at this scale, your four football fields away at Alpha Centauri. The entire Milky Way galaxy at this scale will be bigger than North America.

Sarah Al-Ahmed: That definitely puts it into context. But it's also funny. It speaks to the American need to turn everything into football fields for context comparison.

Bruce Betts: Well, yeah. But I figure a football field with American football is about the same length as a soccer field known as football elsewhere. I'm turning it into football fields, but it's more of a generic football field. That was way too much explanation. All right. We move on to the trivia contest and we asked you about the wonderful picture, what astronaut included his two rescue dogs in his official NASA photo. How do we do and do we have any fun stories?

Sarah Al-Ahmed: We got a lot of answers on this one because obviously it involves puppies and everybody loves dogs. People wanted to respond to this one. Across the board, everyone agrees that this is the best astronaut photo. I hope other astronauts bring dogs or cats into other photos. But the answer is Leland Melvin. He's not only an astronaut, but a dog rescue advocate. In 2008 when he was selected to be on a space shuttle mission, it was a perfect time to take a new astronaut photo and people are allowed to bring some family members in there, but he wanted to bring his four-legged family members with him. He brought two rescue dogs, his dogs Jake and Scout at the time. I'm going to put a copy of this picture on the page for this planetary radio episode at so you can see how cute this is because these dogs are so adorable.

Bruce Betts: Yeah. It's adorable. That was really good. My impression was there was some sneaking involved in getting them onto JSC, but I'm not ...

Sarah Al-Ahmed: I've heard rumors that it was sneaky, sneaky, but it would be really fun to bring him on the show sometime and ask him about his caper with pups. How do you get dogs into your astronaut photo? Not because I want to know or anything. But our winner this week is Ertan Yuzak from Phoenix, Arizona, USA. Ertan, you've just won a Good Night Oppy 12 ounce thermal mug. We will send that to you. We did. We got some really cute dog stories and things like that. But just across the board, everyone says it is the official best astronaut photo of all time. I like this one too because it does. It pertains to football. Daniel Kulp from Fort Walton Beach, Florida wanted us to let everyone know that Leland Melvin was also a football player prior to becoming an astronaut.

Bruce Betts: Yeah.

Sarah Al-Ahmed: He said basically he was a receiver who took going deep to a next level.

Bruce Betts: Nah.

Sarah Al-Ahmed: Ah.

Bruce Betts: Leland, go deep. No man, not that deep. Switching gears, Mars missions is the topic. Mars was a tricky little bugger back in the day. How many missions to Mars were tried but failed for any reason before Mariner 4 was the first successful mission at Mars? How many failed missions were attempted to Mars before Mariner 4 succeeded? Go to

Sarah Al-Ahmed: You have until Wednesday, March 1st at 8:00 a.m. Pacific time to get us the answer. Remember, space is hard. There's probably quite a number of these. But whoever wins this is going to be receiving another Good Night Oppy 12 ounce thermal mug. I know several people really, really wanted this as the prize. Here's your second chance to get one. For anyone who hasn't had the pleasure of watching the Good Night Oppy documentary, it's on Amazon Prime video and it's all about the Opportunity Rover. If you love Mars or you need a moment to feel inspired or just need a good ugly cry about robots on another planet, I really recommend this one. It was adorable.

Bruce Betts: Everybody go out there, look up the night sky and think about tears falling in popcorn. Thank you. I'm sorry. Goodnight.

Sarah Al-Ahmed: We've reached the end of this week's episode of Planetary Radio, but we'll be back next week to tell you more about the Canadian Space Agency's upcoming Lunar Rover. Planetary Radio is produced by The Planetary Society in Pasadena, California and is made possible by our stellar members. You can join us to help support missions like Mars Sample Return at Mark Hilverda and Rae Paoletta are our associate producers. Andrew Lucas is our audio editor. Josh Doyle composed our theme, which was arranged and performed by Pieter Schlosser. And until next week, Ad Astra.